Serotonin Hypothesis Debunked Yet Again

Well, maybe not debunked, but both CL Psych and John Grohol at Psych Central answer a commenter at CL's site who asserted that serotonin deficits explain depression and that there's lots of good evidence that SSRIs are just what the doctor ordered.

CL Psych's response:

"Despite making excellent marketing copy, studies have found no consistent abnormality in serotonin in depressed people. Doubt me? Read this excellent article by Lacasse and Leo (published in PLoS Medicine) that describes the gap between the marketing of serotonin in depression and the scientific literature."

I encourage one and all to download and read the PLoS paper, which is easily digestible and lays out much of the scientific literature on the matter.

But aren't SSRIs super-awesome for treating depression?

"Try that about 80% of the drug effect is replicated by placebo – there is about a 20% difference in efficacy between placebo and antidepressant (Kirsch et al., 2002). Is that “great evidence” of efficacy? It’s more encouraging than 0% better than placebo, but I remain less than fully convinced. And about those sexual side effects and increased risk of suicidal thinking and suicide attempts… If depression was really due to poor serotonin function, then one would expect treatments that increase serotonin transmission would have a much stronger advantage over placebo."

Now, it's Grohol's turn:

"The upshot of the entry is this — serotonin deficiencies do not directly cause depression. There is obviously some relationship there, but what it is isn’t nearly as strong as originally thought, and may not even be a primary or key ingredient of depression."

I'd get into this further myself but my time is extremely limited today. Comment away, readers. BTW, I will be approving comments sporadically after about Noon west coast time, as I am heading out of town after that till Saturday and my computer access will be hit and miss.